<html>
<head>
<title>Favicon</title>
<link id="favicon" rel='icon' type='image/png' />
<script>
  var params = new URLSearchParams(window.location.search);
  var favicon = document.getElementById('favicon')
  if (params.has("favicon")) {
    favicon.href = params.get("favicon");
  } else {
    favicon.href = 'favicon.png'
  }
</script>
</head>
</html>
